Tension device



April 18, 1967 J. F. BLANDINO 3,314,623

TENSION DEVICE Filed Jan. 22, 1965 JAMES E BLANDINO INVENTOR.

ATTORNEY United States Patent 3,314,623 TENSION DEVICE James F. Blandino, Lynn, Mass, assignor to Sylvania Electric Products Inc., a corporation of Delaware Filed Jan. 22, 1965, Ser. No. 427,242 2 Claims. (Cl. 242-5 4) This invention relates to tension devices and more particularly to tension devices employed with the intermittent feeding of segments of a material from a supply thereof.

Many different types of tension devices have been developed over the years, each designed primarily to do a particular job with a particular type of material being fed. The nature of some materials and the requirements associated with the feeding thereof are such that there are few if any critical tolerances requiring any great degree of engineering design. Such however is not the case with respect to the feeding of filament support wire in the manufacture of electric lamps and the like.

Heretofore a friction device has been employed in the feeding of filament support wire from a spool in the manufacture of electric lamps and the like. The force applied by these friction devices has to be great enough to bring the spool to a dead stop when the feeding stroke is terminated in order to prevent the development of slack in the Wire being fed. In the feeding of filament support Wire possessing relatively high tensile strength, the magnitude of the force needed to bring the spool to a dead stop as required presented no significant problem. However, such is not the case Where real fine filament support Wire having a relatively low tensile strength is concerned. The critical point is reached when the force needed to bring the spool to a dead stop is greater than the tensile strength of the wire being fed. In thi critical area, excessive wire breakage precludes the .use of these friction devices.

In view of the foregoing, a principal object of this invention is to provide a tension device which will function effectively with the intermittent feeding of segments of material having a relatively low tensile strength.

Another object of this invention is to provide a tension device which does not require the application of a frictional force to the material being fed great enough to bring the spool of material to a dead stop after each intermittent feeding of a segment thereof.

These and other objects, advantages and features are attained, in accordance with the principles of this invention, by using a spring-loaded pawl and ratchet arrangement in which the ratchet is keyed to the spool of material and the pawl is spring-loaded against the ratchet and direction of rotation, the ratchet teeth being placed in reverse direction of rotation. As the material is fed, the spring on the pawl, acting against the direction of rotation, keeps tension on the material. When the feeding is interrupted, the spool over-rotates a small amount due to inertia forces, but the spring on the pawl rewinds the spool to give back-tension on the material. The force exerted by the spring on the pawl needs to be only a fraction of the force previously needed to eliminate overtravel. This same back-tension force which rewinds the spool also prevents the material from creeping forward due to vibration or other forces when for example, feeding is latched out. A stop is provided to prevent the pawl from leaving the ratchet when there is no material to be fed.

In the accompanying drawing illustrating a specific embodiment of the invention, FIGURE 1 is an elevational view of a tension device embodying the principles of this invention illustrated in association with an anti-rollback device.

FIGURE 2 is a plan view of the apparatus illustrated in FIGURE 1.

Referring now to the accompanying drawing, the pawl and ratchet arrangement of this invention is organized about a bracket 2 secured to and depending from a support bar 4. A post 6 extends through and is supported by the bracket 2. A ratchet wheel 8 and a spool holder 10 are pinned to a bushing 12 which is rotatably supported on post 6. A spool 14 of filament support wire 1 is mounted on the spool holder 10. A pawl 16 is pivotally supported at 18 on bracket 2 and is in operative engagement with the teeth of ratchet wheel 8. The pawl 16 is spring-loaded in a direction counter to the direction of rotation of the ratchet wheel 8 by spring 20. One end of spring 20 is supported by spring post 22 on the pawl. The other end of the spring 20 is attached to spring post 24 mounted in bracket 2. A pin 26 projecting from a face of the bracket 5 lies in the path of the pawl 16 and limits the rotational movement thereof effected by the spring 20.

Wire 1 from the spool friction device mounted on support bar 4. The friction 32, a side block 24, and a to the holder plate 30. A mounted on a shoulder screw 40 which extends into both the main block 32 and the side block v34. The lower end of the roll release 38 is bifurcated and a roll 42 is disposed therebetween and constrained by a roll restrainer 44 depending from the shoulder screw 40. Wire 1 is fed from the spool 14, through guide block 36, through an aperture provided therefor in the main block 32, and across the top face of the holder plate 30 and underneath the roll 42. The wire is then fed through an aperture in a guide block 46 and thorugh snout 48. Guide block 46 is mounted directly on the holder plate 30 and the snout 48' is fitted in a snout shoulder 50 mounted on an arm 52 which is attached to the holder plate 30.

A stop 54 is mounted on a pivot 56 attached to the top of the side block 34 by a clamp 58. A tail portion 54a of stop 54 is normally in vertical alignment with and spaced from a tail portion 38a of the roll release 38. One end of a compression spring 60 is seated: in the top face of side block 34 and the other end thereof is seated in tail portion 38b of the roll released 38.

The preparation of the above-described apparatus for operation will now be described. The first step is to clear the one way friction device for the threading therethrough of the free end of filament support wire 1 from the spool 14 on the spool holder 10. This is accomplished by rotating the stop 54 sufiiciently to displace the tail 54a thereof from vertical alignment with the tail 38a of roll release 38. The roll release 38 is then rotated clockwise about its pivot, shoulder screw 40. This compresses spring 60 and trees roll 42. The stop 54 is then returned to its normal position with the tails 38a and 54a in vertical alignment. The free end of filament support Wire 1 is fed through guide block 36, an aperture provided therefor in the main block 32, and across the top face of the holder plate 30 and underneath the roll 42. The wire is then fed through an aperture in guide block 46 and through snout 48 until the free end projects beyond the tip of the snout.

The wire is now ready to be fed. The tension device of this invention is designed primarily for use with a wire pulling apparatus, i.e., one in which segments of wire are intermittently drawn off of a roll or spool. An apparatus of this type is disclosed in US. Patent 3,088,498 which issued May 7, 1963. As the wire 1 is drawn off of the spool 14 and through the snout 48, the movement of the wire will cause the roll 42 to be displaced in the direction of the movement of the wire. Since the roll 42 is trapped by the roll release 38, the displacement of the roll 42 bv the movement of the wire will cause the roll release 38 to rotate about its pivot 40 until the tail 14 is fed through a one way a holder plate 30 attached to device includes a main block guide block 36, all attached roll release 38 is pivotally 3 38a thereof strikes the tail 54a of stop 54. During this rotational movement of the roll release 38, the spring 60 is compressed.

As the wire 1 is drawn from the spool 14, back tension is maintained on the spool by spring 20 through pawl 16 and ratchet wheel 8. When the pull on the wire terminates, the spring 60 expands and thus causes counterclockwise rotation of the roll release 38. This causes a wedging of the roll 42 against the wire 1 and prevents further advancement thereof. Overtravel of the spool of wire 14 is automatically compensated for by the spring 20. While the wire is being unwound or drawn from the spool, the ratchet wheel 8 rotates with the spool 14 and thus displaces the pawl 16. This displacement of the pawl 16 extends the spring 20. Thus, if there is any slack in the Wire between the roll 42 and spool 14 after the roll 42 wedges against the wire and counter-clockwise rotation (as viewed in FIG. 1) of the spool 14 has terrninated, the loaded spring 20 draws the pawl 16 counterclockwise. Since the pawl 16 is in engagement with the ratchet wheel 8 and since the ratchet wheel 8 and spool 14 are mechanically connected to one another, this causes clockwise rotation of the ratchet wheel and spool to thus take up the slack. To preclude malfunctioning of the tension device due to some abnormal circumstance or condition, the counter-clockwise rotation of the pawl 16 by the spring 20 is limited by stop 26.

What I claim is:

1. In combination with a wire pulling apparatus in which segments of wire are intermittently drawn ofl? of a spool of wire and a one way-friction device which prevents further movement of the wire after any given segment of wire has been drawn, a tension device comprising:

a base member;

a post mounted on said base member;

a ratchet wheel freely rotatable on said post, said spool of wire being rotatable on said post in unison with 'said ratchet wheel;

a pawl pivotally mounted on said base member and in engagement with said ratchet wheel; a spring loading said pawl in a direction opposite to the normal direction of rotation of said ratchet wheel,

said teeth and said pawl having coacting surfaces shaped in a manner to permit said pawl to override said teeth when said spool is being rotated in a normal direction during the time wire is being pulled therefrom, and when slack develops in the wire said pawl being urged by said spring to engage one of said teeth and rotate said spool in an opposite direction to take up the slack.

2. A tension device for taking up the slack in a spool 01 wire from which segments of wire are intermittently drawn, said tension device comprising:

a ratchet wheel rotatable in unison with said spool of wire;

a pivotally mounted pawl disposed in cooperative relationship with respect to said ratchet wheel; a spring loading said pawl in a direction opposite to the normal direction of rotation of said ratchet wheel,

said teeth and said pawl having coacting surfaces shaped in a manner to permit said pawl to override said teeth when said spool is being rotated in a normal direction during the time wire is being pulled therefrom, and when slack develops in the wire said pawl being urged by said spring to engage one of said teeth and rotate said spool in an opposite direction to take up the slack.

References Cited by the Examiner UNITED STATES PATENTS 6/1891 Walters 242-129.3 4/1936 Meisel 226l43 X 9/1939 Humphrey 2421 17 X 

2. A TENSION DEVICE FOR TAKING UP THE SLACK IN A SPOOL OF WIRE FROM WHICH SEGMENTS OF WIRE ARE INTERMITTENTLY DRAWN, SAID TENSION DEVICE COMPRISING: A RATCHED WHEEL ROTATABLE IN UNISON WITH SAID SPOOL OF WIRE; A PIVOTALLY MOUNTED PAWL DISPOSED IN COOPERATIVE RELATIONSHIP WITH RESPECT TO SAID RATCHET WHEEL; A SPRING LOADING SAID PAWL IN A DIRECTION OPPOSITE TO THE NORMAL DIRECTION OF ROTATION OF SAID RATCHET WHEEL, SAID TEETH AND SAID PAWL HAVING COATING SURFACES SHAPED IN A MANNER TO PERMIT SAID PAWL TO OVERRIDE SAID TEETH WHEN SAID SPOOL IS BEING ROTATED IN A NORMAL DIRECTION DURING THE TIME WIRE IS BEING PULLED THEREFROM, AND WHEN SLACK DEVELOPS IN THE WIRE SAID PAWL BEING URGED BY SAID SPRING TO ENGAGE ONE OF SAID TEETH AND ROTATE SAID SPOOL IN AN OPPOSITE DIRECTION TO TAKE UP THE SLACK. 